Article

Journal of Clinical Monitoring and Computing

, Volume 22, Issue 1, pp 67-74

First online:

Prospective Investigation into the Influence of Various Stressors on Skin Impedance

  • Michael WinterhalterAffiliated withDepartment of Anaesthesiology, Hannover Medical School Email author 
  • , Jörg SchillerAffiliated withDepartment of Anaesthesiology, Hannover Medical School
  • , Sinika MünteAffiliated withDepartment of Anaesthesiology, Hannover Medical SchoolHelsinki University Clinics, Children’s Hospital
  • , Michael BundAffiliated withDepartment of Anaesthesiology, Hannover Medical School
  • , Ludwig HoyAffiliated withDepartment of Biometry, Hannover Medical School
  • , Christoph WeilbachAffiliated withDepartment of Anaesthesiology, Hannover Medical School
  • , Siegfried PiepenbrockAffiliated withDepartment of Anaesthesiology, Hannover Medical School
  • , Niels Rahe-MeyerAffiliated withDepartment of Anaesthesiology, Hannover Medical School

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Abstract

Background

The control mechanisms during general anesthesia include circulation parameters and vegetative reactions. A possible way to quantify vegetative reactions is to measure the impedance of the skin. An activation of the eccrine sweat glands via sympathetic sudomotor fibers induces a secretion of sweat, which generates a drop in skin impedance. The aim of the present study was to investigate the influence which different stressors and measurement electrodes have upon skin impedance.

Material and Method

The changes in skin impedance and were measured after application of various stimuli (T1 value at rest, T2 acoustic stimulus, T3 visual stimulus, T4 tactile stimulus, T5 pain stimulus, T6 Valsalva manoeuvre, T7 forced inspiration/expiration). About 62 awake subjects underwent four standardized test sequences, during which several types of electrodes and recording sites (palmarly, plantarly) were explored.

Results

All physiological (T6–T7) and external stimuli (T2–T5) led to significant changes in skin impedance (14.9 ±α8.2 kΩ) and heart rate. These changes happened independently of BMI, gender and measurement electrode types. The time it took to react to the stimuli was significantly shorter for palmar applications than that obtained from plantar sites. The reaction times were as follows: palmarly 1.2 ±α0.5 seconds for solidgel electrodes and 1.15 ±±0.5 seconds for hydrogel electrodes, plantarly 2.3 ±±1.0 seconds for solidgel electrodes and 2.21 ±±1.2 seconds for hydrogel electrodes. The forced inspiration and expiration manoeuvres generated greater variations in skin impedance than did pain stimulus and acoustic stimulus. Measurements that were performed with solidgel electrodes revealed significantly greater average decreases in skin impedance following exposure to a stimulus.

Conclusion(s)

External, but primarily also physiological stressors, generate direct and reproducible variations in skin impedance. Solidgel ECG electrodes should be used for all measurements.

Keywords

skin impedance anesthesia stress measurement